The present invention relates to a monitoring apparatus for a laser beam. Furthermore, the invention relates to a laser apparatus for emitting laser light, which apparatus comprises a monitoring apparatus. Finally, the invention relates to a method for monitoring a laser beam.
Technical systems in which laser radiation is used require that this laser beam propagates on a previously established path. If the beam departs from this previously established path, for example in the event of an error, functional failure of the system and/or damage to the system can occur. This can happen as the result of both direct and indirect, i.e. reflected laser radiation. For this reason, it is necessary to check whether or not the laser beam is situated on the previously established path.
From the state of the art, light-sensitive sensors are known, with which sensors it is possible to check whether the laser beam is situated on the previously established path, if the number and arrangement of the sensors is appropriate. Depending on the geometry of the space to be monitored, very many sensors can be required for this purpose, because every sensor has only a limited detection range. It is therefore necessary to place multiple sensors so that their vision ranges supplement one another in such a manner that in total, the entire space to be monitored can be observed. Aside from the plurality of sensors, overlaps of the vision ranges are necessarily accepted in this regard, without achieving real redundancy to reduce the failure probability of the system.
One object of the invention is to make available a monitoring apparatus for a laser beam, which apparatus allows secure and reliable monitoring of a laser beam, along with simple and cost-advantageous production.
This object may be accomplished by a monitoring apparatus for a laser beam, which apparatus comprises a body and a sensor. The body has a passage opening, wherein it is provided, in particular, that the laser beam can be passed through this passage opening. The sensor is disposed on the body. According to the invention, it is provided that impact of the laser beam onto the body can be detected by the sensor. In this manner, monitoring of the laser beam can be implemented in such a manner that during normal operation, the laser beam is passed through the passage opening. If, instead, the laser beam is deflected and impacts the body, this is recognized by the sensor. Thereby an error case can be recognized. In this regard, the passage opening can have any desired shape.
The dependent claims have further advantageous developments of the invention as their content.
Preferably, it is provided that the body is a hollow profile having a closed cross-section. In this regard, the hollow profile can assume any desired geometrical shapes. Particularly advantageously, the hollow profile is a light guide. The use of a hollow profile as the body allows reduction of the monitoring region of the laser beam to a two-dimensional plane. Thus, the hollow profile forms a closed geometrical figure in the two-dimensional plane, wherein it is provided that the laser beam impacts this two-dimensional plane perpendicularly during normal operation. Thus the laser beam is represented by a point in the two-dimensional plane. Monitoring is therefore restricted to determining whether the point lies within the geometrical body or impacts the geometrical body. Therefore, monitoring is very simple, particularly in view of the monitoring of an entire three-dimensional space by means of a plurality of light-sensitive sensors used in the state of the art.
It is advantageous if the hollow profile has a mantle surface, wherein the sensor is disposed on the mantle surface. In this regard, it is particularly provided that the sensor is a light-sensitive sensor that recognizes coupling of light of the laser beam into the hollow profile. Therefore the sensor is able to detect when the laser beam impacts the hollow profile. For this purpose, at least one light having the wavelength of the laser beam can be recognized using the sensor.
Likewise, it is preferably provided that the hollow profile has a first face surface and a second face surface, wherein the second face surface has a greater roughness than the first face surface. Due to the different surface roughnesses, which are particularly selected by taking the index of refraction of the material of the hollow profile into consideration, the laser beam can be coupled into the hollow profile. Thereby the laser beam is always guided onto a predefined surface area of the hollow profile, independent of its angle of incidence into the body. Because it is particularly provided that the sensor is disposed on the mantle surface of the hollow profile, the laser beam is advantageously guided onto this mantle surface. Thereby it is particularly possible that the body has any desired shape, because the laser beam can always be guided onto a predefined surface area of the hollow profile.
It is advantageous if the hollow profile is produced from a light-conducting material, preferably from acrylic glass. This allows simple and cost-advantageous production of the hollow profile, wherein at the same time, working of surface roughnesses of the hollow profile is made possible. In particular, acrylic glass is optimally suitable for coupling in light of the laser beam.
Alternatively, the body is an electrical conductor. In this regard, the electrical conductor is advantageously formed into at least one winding. The sensor in turn is configured for measuring a resistance of the electrical conductor. At high laser power, coupling of laser light into the body might no longer be possible, because the intensity of the laser beam would destroy or damage the body. Therefore the body is preferably an electrical conductor that is damaged or severed when the laser beam hits it. In turn, by forming the electrical conductor into at least one winding, the principle described above is achieved, that a closed two-dimensional shape is present, wherein the laser beam intersects the two-dimensional shape at a right angle under normal conditions. If an error case is present, the laser beam impacts the electrical conductor, thereby damaging it. The resistance of the conductor is thereby changed, so that the sensor can detect, by measuring the electrical resistance of the conductor, whether the latter is damaged or destroyed. Once again, it can be recognized, in this manner, whether the laser beam has hit the body. Detection of the electrical resistance can take place either by measuring the resistance or by emitting a test signal, wherein in the latter case, a measure of the resistance can be determined using the test signal that is received after it has passed through the electrical conductor.
It is particularly advantageous if the electrical conductor is structured in a circular shape, so that a round passage opening is present. This simplifies the production and installation of the body configured as an electrical conductor.
Likewise, it is preferably provided that the body is a light wave guide. Particularly advantageously, the light wave guide comprises at least one glass fiber. In this regard, the light wave guide is formed into at least one winding. The sensor in turn is configured for receiving a message transmitted into the light wave guide. In this regard, the monitoring principle is analogous to the case of the electrical conductor. In normal operation, the laser beam is guided perpendicular to a cross-section of the winding, so that it runs through the passage opening formed by the winding. If the laser beam is deflected, however, it impacts the light wave guide and damages or destroys it. Therefore the sensor cannot receive a message transmitted into the light wave guide, or cannot receive it correctly. It is particularly advantageous if the sensor is also configured for emitting the message into the light wave guide, wherein the sensor transmits a message into the light wave guide periodically, in particular. If this message is not received or not received correctly, a conclusion can be drawn concerning damage to the light wave guide and therefore concerning an error case in the operation of the laser beam. The advantage of using the light wave guide particularly lies in the fact that the monitoring apparatus cannot be influenced by external electromagnetic radiation. Likewise, the monitoring apparatus itself does not emit any electromagnetic radiation. Therefore the monitoring apparatus is very robust against interference and can be used even in environments that are not allowed to be disrupted by electromechanical radiation.
The invention furthermore comprises a laser apparatus that comprises a laser source and a previously mentioned monitoring apparatus. In this regard, it is provided that the laser source is configured in such a manner that the laser beam is emitted through the passage opening of the body of the monitoring apparatus. In particular, the body has a closed cross-section, wherein the laser beam is emitted by the laser source in such a manner that the laser beam intersects the cross-section perpendicularly. The laser apparatus can therefore be operated in particularly secure and reliable manner, because an error case can be detected by the monitoring apparatus. At the same time, the laser apparatus can be produced in very simple and cost-advantageous manner, because the monitoring apparatus, in particular, is structured in simple and cost-advantageous manner.
Finally, the invention relates to a method for monitoring a laser beam. The method comprises the following steps: First, a laser beam is emitted by a laser source. In this regard, the laser beam is guided through a passage opening of a body. In particular, propagation of the laser beam takes place concentrically to a center axis of the passage opening. Subsequently, recognition of coupling of the emitted laser beam into the body takes place. Alternatively or in addition to this, recognition of damage to the body by the emitted laser beam takes place. The two stated steps of recognition can be carried out alternatively or simultaneously. In every case, a deviation of a propagation direction of the laser beam can be recognized, because the beam is no longer guided through the passage opening but rather onto the body. Thereby it can be recognized that an error case exists in the emission of the laser beam.
The invention will now be described in detail, using exemplary embodiments, making reference to the attached drawings.